This invention relates to an ophthalmoscope, i.e. an instrument for viewing the interior of the eye. More particularly, the invention provides an ophthalmoscope having a new lamp element that illuminates the eye fundus in a manner that minimizes interference with the viewing of the fundus through the crystalline lens of the eye.
The invention thus provides a new wide-angle ophthalmoscope having a superior field of view and a superior observable field as compared with prior devices of this kind. The field of view is the area of the fundus covered by the viewer, or viewing instrument, in any direction of observation in a single image; and the observable field is the area of the fundus beyond which the ophthalmoscope is unable to reach. The invention also provides an improvement in the control, and consequently in the uniformity, of the illumination over the fundus.
Due to these and other advantages set forth below, an ophthalmoscope embodying the invention enables superior viewing of the entire retina, and photographing it, in a single image. The ophthalmoscope in addition requires significantly less dilation of the patient's pupil than prior wide-angle ophthalmoscopes. This enables ophthalmologic examination in situations where it previously was not possible due to restrictions on the allowable dilation, as is the case with patients suffering from diabetes.
The co-pending applications noted above describe wide-angle ophthalmoscopes having improved constructions for both illumination and viewing exclusively through the crystal lens of the patient, i.e. of the eye being observed. However, these prior wide-angle ophthalmoscopes require precise construction and precise placement on the patient's eye, as well as significant dilation of the patient's pupil. Also, there is often a noticeable diminution of illumination at the periphery of the fundus.
Accordingly, it is an object of this invention to provide an optical, fundus-viewing instrument in which the lamp element imposes less constraint on the viewing lens than in prior devices of this kind.
It is also an object of the invention to provide a wide-angle fundus-viewing instrument having a lamp element that provides control over the illumination of the fundus and particularly which illuminates the fundus with high uniformity.
A further object of the invention is to provide a wide-angle ophthalmoscope that requires relatively small dilation of the pupil of the eye being examined.
Another object of the invention is to provide an ophthalmologic device of the above character which requires less precision and hence less cost to fabricate than comparable prior devices and which is relatively easy to use.
It is also an object of the invention to provide an ophthalmologic device of the above character having no or fewer lamp elements according to the desired illumination, which direct illumination through the lens of the patient's eye.
Other objects of the invention will in part be obvious and will in part appear hereinafter.